Water treatment system and method

ABSTRACT

A treatment system provides treated or softened water to a point of use by removing at least a portion of any undesirable species contained in water from a water source. The treatment system can be operated to reduce the likelihood of formation of any scale that can be generated during normal operation of an electrochemical device. The formation of scale in the treatment system, including its wetted components, may be inhibited by reversing or substituting the flowing liquid having hardness-causing species with another liquid having a low tendency to produce scale, such as a low LSI water. Various arrangements of components in the treatment system can be flushed by directing the valves and the pumps of the system to displace liquid having hardness-causing species with a liquid that has little or no tendency to form scale.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, generally, to a system and method ofpurifying or treating a fluid and, more particularly, to a watertreatment system incorporating an electrochemical device and a reservoirfor delivering treated water to a point of use and a method of operatingand flushing the water treatment system.

2. Description of Related Art

Water that contains hardness species such as calcium and magnesium maybe undesirable for some uses in industrial, commercial and householdapplications. The typical guidelines for a classification of waterhardness are: zero to 60 milligrams per liter (mg/l) as calciumcarbonate is classified as soft; 61 to 120 mg/l as moderately hard; 121to 180 mg/l as hard; and more than 180 mg/l as very hard.

Hard water can be softened or treated by removing the hardness ionspecies. Examples of systems that remove such species include those thatuse ion exchange beds. In such systems, the hardness ions becomeionically bound to oppositely charged ionic species that are mixed onthe surface of the ion exchange resin. The ion exchange resin eventuallybecomes saturated with ionically bound hardness ion species and must beregenerated. Regeneration typically involves replacing the boundhardness species with more soluble ionic species, such as sodiumchloride. The hardness species bound on the ion exchange resin arereplaced by the sodium ions and the ion exchange resins are ready againfor a subsequent water softening step.

Other systems have been disclosed. For example, Dosch, in U.S. Pat. No.3,148,687 teaches a washing machine including a water softeningarrangement using ion exchange resins. Similarly, Gadini et al., inInternational Application Publication No. WO00/64325, disclose ahousehold appliance using water with an improved device for reducing thewater hardness. Gadini et al. teach of a household appliance having acontrol system, a water supply system from an external source and asoftening system with an electrochemical cell. McMahon, in U.S. Pat. No.5,166,220, teaches of a regeneration of ion exchange resin with a brinesolution in a water softening process.

Electrodeionization (EDI) can be used to soften water. EDI is a processthat removes ionizable species from liquids using electrically activemedia and an electrical potential to influence ion transport. Theelectrically active media may function to alternately collect anddischarge ionizable species, or to facilitate the transport of ionscontinuously by ionic or electronic substitution mechanisms. EDI devicescan include media having permanent or temporary charge and can beoperated to cause electrochemical reactions designed to achieve orenhance performance. These devices also include electrically activemembranes such as semi-permeable ion exchange or bipolar membranes.

Continuous electrodeionization (CEDI) is a process that relies on iontransport through electrically active media (electroactive media). Atypical CEDI device includes alternating electroactive semi-permeableanion and cation selective membranes. The spaces between the membranesare configured to create liquid flow compartments with inlets andoutlets. A transverse DC electrical field is imposed by an externalpower source through electrodes at the bounds of the compartments. Insome configurations, electrode compartments are provided so thatreaction product from the electrodes can be separated from the otherflow compartments. Upon imposition of the electric field, ions in theliquid to be treated in one compartment, the ion-depleting compartments,are attracted to their respective attracting electrodes. The ionsmigrate through the selectively permeable membranes into the adjoiningcompartments so that the liquid in the adjoining ion-concentratingcompartments become ionically concentrated. The volume within thedepleting compartments and, in some embodiments, within theconcentrating compartments, includes electrically active orelectroactive media. In CEDI devices, the electroactive media mayinclude intimately mixed anion and cation exchange resins. Suchelectroactive media typically enhances the transport of ions within thecompartments and may participate as a substrate for controlledelectrochemical reactions. Electrodeionization devices have beendescribed by, for example, Giuffrida et al. in U.S. Pat. Nos. 4,632,745,4,925,541 and 5,211,823, by Ganzi in U.S. Pat. Nos. 5,259,936 and5,316,637, by Oren et al. in U.S. Pat. No. 5,154,809 and by Kedem inU.S. Pat. No. 5,240,579.

Other systems that can be used to demineralize water have beendescribed. For example, Gaysowski, in U.S. Pat. No. 3,407,864, teachesof an apparatus that involves both ion exchange and electrodialysis.Johnson, in U.S. Pat. No. 3,755,135, teaches of a demineralizingapparatus using a DC potential.

SUMMARY OF THE INVENTION

The present invention is directed to a treatment system. The treatmentsystem can comprise an electrochemical device comprising a firstcompartment and a second compartment, a first liquid circuit fluidly afirst compartment inlet and a first pump, a second liquid circuitfluidly connecting a second compartment outlet to a second compartmentinlet and a second pump and a third liquid circuit fluidly connectingthe second compartment inlet and the second pump.

In accordance with one or more embodiments, the present inventionprovides a treatment system. The treatment system can comprise anelectrochemical device comprising a first compartment comprising a firstcompartment outlet and a first compartment inlet and a secondcompartment comprising a second compartment outlet and a secondcompartment inlet, a first pump fluidly connectable to the firstcompartment outlet and to the first compartment inlet, a second pumpfluidly connectable to the second compartment outlet and to the secondcompartment inlet, and a circulation line fluidly connectable to atleast one of the first or second compartment outlets. Theelectrochemical device fluidly is typically connected to a point ofentry.

In accordance with one or more embodiments, the present inventionprovides a method of treating a liquid. The method can compriseestablishing a first liquid circuit having liquid to be treated flowingtherein from a reservoir to a first compartment inlet of anelectrochemical device through a first pump, establishing a secondliquid circuit having a concentrating liquid flowing therein from asecond compartment outlet of the electrochemical device to a secondcompartment inlet through a second pump, and establishing a third liquidcircuit having liquid to be treated flowing therein from the reservoirto the second compartment inlet through the second pump.

In accordance with one or more embodiments, the present provides amethod of treating water. The method can comprise passing at least aportion of water to be treated through a depleting compartment of anelectrochemical device through a first pump to produce the treatedwater, circulating the concentrated stream through a concentratingcompartment of the electrochemical device through a second pump, andcirculating the concentration stream through the concentratingcompartment through the first pump.

In accordance with one or more embodiments, the present inventionprovides a method of treating water. The method can comprise passingwater to be treated through an electrochemical device to produce treatedwater, storing at least a portion of the treated water in a waterreservoir, and flushing a concentrating compartment of theelectrochemical device with the treated water.

In accordance with one or more embodiments, the present inventionprovides the method of facilitating water purification. The method cancomprise providing an electrochemical device comprising a firstcompartment and a second compartment; providing a first pump fluidlyconnectable to at least one of a water reservoir, a first compartmentoutlet and a first compartment inlet; providing a second pump fluidlyconnectable to at least one of the water reservoir, a second compartmentoutlet and a second compartment inlet; and providing a circulation linefluidly connectable to at least one of the first and second compartmentoutlets.

In accordance with one or more embodiments, the present inventionprovides a treatment system. The treatment system can comprise anelectrochemical device comprising a first compartment and a secondcompartment, means for flowing a liquid to be treated from a waterreservoir through the first compartment and circulating a concentratingliquid through the second compartment and means for flowing the liquidto be treated from the water reservoir through the second compartmentand circulating the concentrating liquid through the first compartment.

Other advantages, novel features and objects of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings, which areschematic and are not intended to be drawn to scale. In the figures,each identical or substantially similar component that is illustrated invarious figures is represented by a single numeral or notation. Forpurposes of clarity, not every component is labeled in every figure, noris every component of each embodiment of the invention shown whereillustration is not necessary to allow those of ordinary skill in theart to understand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred, non-limiting embodiments of the present invention will bedescribed by way of example and with reference to the accompanyingdrawings, in which:

FIG. 1 is a schematic flow diagram of a treatment system showing areservoir in line with an electrochemical device in accordance with oneor more embodiments of the invention;

FIG. 2A is a schematic flow diagram for treatment system illustrating afirst liquid circuit flowing therein in accordance with one or moreembodiments of the invention;

FIG. 2B is a schematic flow diagram of a treatment system illustrating asecond fluid circuit flowing therein in accordance with one or moreembodiments of the invention;

FIG. 2C is a schematic flow diagram of a treatment system illustrating athird fluid circuit flowing therein in accordance with one or moreembodiments of the invention;

FIG. 2D is a schematic flow diagram of a treatment system illustrating afourth liquid circuit flowing therein in accordance with one or moreembodiments of the invention;

FIG. 3A is a schematic flow diagram of a treatment system illustratingthe flow of flushing fluid flowing therein in accordance with one ormore embodiments of the invention;

FIG. 3B is a schematic flow diagram of a treatment system illustratingthe flow of flushing fluid flowing therein in accordance with one ormore embodiments of the invention;

FIG. 4 is a schematic flow diagram of a treatment system according toanother embodiment of the present invention as described in the Example;and

FIG. 5 is a graph showing the measured conductivity of the treatmentsystem shown schematically in FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

United States Patent Applications titled WATER TREATMENT SYSTEM ANDMETHOD by Wilkins et al. and filed on even date herewith; WATERTREATMENT SYSTEM AND METHOD by Jha et al. and filed on even dateherewith; WATER TREATMENT SYSTEM AND METHOD by Ganzi et al. and filed oneven date herewith; WATER TREATMENT SYSTEM AND METHOD by Freydina et al.and filed on even date herewith; WATER TREATMENT SYSTEM AND METHOD byWilkins et al. and filed on even date herewith; WATER TREATMENT SYSTEMAND METHOD by Freydina et al. and filed on even date herewith; and WATERTREATMENT SYSTEM AND METHOD by Wilkins et al. and filed on even dateherewith are hereby incorporated by reference herein.

The present invention is directed to a purification or treatment systemand method of providing treated water in industrial, commercial andresidential applications. The treatment system provides treated wateror, in some cases, softened water, to a point of use by removing atleast a portion of any undesirable species such as hardness-causingspecies contained in water from a water source, such as municipal water,well water, brackish water and other water sources. The treatment systemcan be operated to reduce the likelihood of formation of any scale orfoulants that are typically generated while producing treated water. Theformation of scale or foulants in the treatment system, including itscomponents, such as any pumps, valves and lines, may be inhibited byreversing or substituting the flowing liquid from one having a hightendency to form scale to a liquid having a low no tendency to producescale, such as a water having a low Langelier Saturation Index (LSI).LSI can be calculated according to, for example, ASTM D 3739.

The treatment system typically receives water from the water source or apoint of entry and purifies the water that may contain undesirablespecies. The treatment system also provides or delivers the treatedwater to a point of use, typically through a water distribution system.The treatment system typically has a reservoir system in line with anelectrochemical device such as an electrodeionization device. Thetreatment system, in some embodiments, also comprises a sensor formeasuring at least one property of the water or an operating conditionof the system. In accordance with other embodiments of the presentinvention, the treatment system also includes a controller for adjustingor regulating at least one operating parameter of the treatment systemor a component of the treatment system such as, but not limited to,actuating valves, energizing pumps or other components of the system.

FIG. 1 is a schematic flow diagram of a treatment system according toone embodiment of the present invention. The treatment system 10 caninclude an electrodeionization device 12 fluidly connected to areservoir system 14, which is typically fluidly connected to a watersource or a point of entry 16. Treatment system 10 typically includes apoint of use 18, which is typically fluidly connected to reservoirsystem 14. According to one embodiment of the present invention,treatment system 10 includes pumps 20 a and 20 b, which can be used topump liquid from reservoir system 14 and, in some cases, circulate aliquid from an outlet to an inlet of electrodeionization device 12through a circulation line 32. In certain embodiments of the invention,treatment system 10 includes valves 22 a, 22 b, 22 c and 22 d that canbe used to direct flow to and from electrodeionization device 12 and toand from reservoir system 14, as well as through pumps 20 a, 20 b and apretreatment filter 24 a and 24 b. In the figures, not all the valveshave been illustrated for purposes of clarity; for example, a valvecontrolling flow of a stream to drain 30 is not shown. In anotherembodiment of the invention, treatment system 10 can include a controlsystem, which typically includes a controller 26, as well as a sensor28. Sensor 28 typically measures an operating parameter or a property ofany the flowing fluids in treatment system 10. Typically, sensor 28sends or transmits the measured parameter to control system 26.

In yet another embodiment of the present invention, control system 26can actuate any valve to direct the flow of liquid in the waterpurification. In some cases, control system 26 can energize the motorsof the pumps in the treatment system. Thus, control system 26 canmonitor and control the operation of the treatment system.

Electrodeionization module or device 12 typically includes ion-depleting(depleting) compartments and ion-concentrating (concentrating)compartments. Adjacent compartments typically have an ion-selectedmembrane positioned therebetween. The assembly of concentrating anddepleting compartments, typically known as the stack, may be inalternating order or in any of various arrangements necessary to satisfydesign and performance requirements. The stack arrangement is typicallybordered by an electrode compartment at one end and another electrodecompartment at an opposite end. Typically, end blocks are positionedadjacent to end plates housing an anode and a cathode in respectiveelectrode compartments. The concentrating and depleting compartments aretypically defined by spacers or structures that offset and support ionselective membranes or selectively permeable membranes. The spacer,along with the selective membrane bonded thereon, define a cavity whichmay serve as a concentrating or a depleting compartment, depending onoperating conditions as explained below.

The concentrating and depleting compartments can be filled with cationexchange resins anion exchange resins or a mixture of both. The cationand anion exchange resins can be arranged as mixtures or as layerswithin any of the depleting, concentrating and electrode compartments sothat a number of layers in a variety of arrangements can be assembled.The use of mixed bed ion exchange resins in any of the depleting,concentrating and electrode compartments the use of inert resin betweenlayers of beds of anionic and cationic exchange resins, as well as theuse of various types of anionic and cationic exchange resins, such asthose described by DiMascio et al., in U.S. Pat. No. 5,858,191, which isincorporated herein by reference in its entirety, is believed to bewithin the scope of the invention.

In operation, a liquid to be treated, typically from an upstream watersource entering the treatment system 10 at point of entry 16, havingdissolved cationic and anionic species, including hardness ion species,can be introduced into reservoir system 14. Liquid to be treated maythen be treated or demineralized in electrodeionization device 12 asdescribed below. The produced treated liquid can then be transferred andstored in reservoir system 14. Treated liquid in reservoir system 14, orat least a portion thereof, can be transferred to point of use 18through a connected, in one embodiment, water distribution system (notshown).

Liquid to be treated typically enters electrodeionization device orstack 12, preferably in a depleting compartment of electrodeionizationdevice 12. An electric field can be applied across the stack through theelectrodes. The applied electric field typically creates a potentialthat attracts cationic and anionic species to their respectiveelectrodes. In this way, the cationic and anionic species tend tomigrate toward their respective attracting electrodes from the depletingcompartment to adjacent compartments, which, in some embodiments, areconcentrating compartments. Selectively permeable membranes betweencompartments serve as barriers preventing further migration of ionicspecies into the next compartment. Thus, the ionic species from a liquidflowing in a depleting compartment can be trapped in an adjacent ornearby concentrating compartment thereby creating a treated liquidexiting the former compartment and a concentrate stream exiting thelatter compartment. Representative suitable ion-selective membranesinclude, for example, web supported using styrene-divinyl benzene withsulphonic acid or quaternary ammonium functional groups, web supportedusing styrene-divinyl benzene in a polyvinylidene fluoride binder, andunsupported-sulfonated styrene and quarternized vinyl benzyl aminegrafts on polyethylene sheet.

In some embodiments of the present invention, the applied electric fieldcan create a polarization phenomenon, which typically leads to thedissociation of water, especially when water is used as liquid to betreated, into hydroxyl and hydrogen ions. The hydroxyl and hydrogen ionscan regenerate the ion exchange resins in the depleting andconcentrating compartments so that removal of the dissolved ionicspecies can occur under substantially ionically neutral conditions andcan be performed continuously and without a separate step forregeneration of exhausted ion exchange resins.

The electric field is typically a direct current applied through theelectrodes deionization device 12. However, any applied electric currentthat can create a bias or a potential difference between one electrodeand another can be used to promote the migration of ionic species.Therefore, an alternating current may be used, provided that there is apotential difference between electrodes that is sufficient to attractcationic and anionic species to their respective attracting electrodes.For example, in one embodiment of the invention, an alternating currentmay be rectified, such as with a diode or a bridge rectifier to convertthe alternating current to a pulsating current having sufficientpotential to attract charged ionic species.

The electroactive media, typically cationic and anionic exchange resins,typically utilized in the depleting compartment and, in some cases, inthe concentrating compartment, can have a variety of functional groupson their surface regions, including, but not limited to, tertiary alkylamino groups and dimethyl ethanolamine. These can also be used incombination with other ion exchange resin materials having variousfunctional groups such as, but not limited to quaternary ammoniumgroups. Other modifications and equivalents should occur to personsskilled in the art using no more than routine experimentation. Forexample, the use of layered beds of ion exchange resin within any of thedepleting, concentrating, and electronic compartments may be used in thepresent invention.

Reservoir system 14 can serve to store or accumulate liquid from pointof entry 16 and can also serve to store treated liquid fromelectrodeionization device 12. Reservoir system 14 can also providetreated water or at least partially treated water, to point of use 18.In some embodiments, reservoir system 14 comprises a vessel, such as apressurized vessel that has inlets and outlets for fluid flow. As usedherein, pressurized refers to any unit operation that has a differentialpressure that is greater than about 2 psi. Accordingly, a pressurizedvessel is a vessel that has a differential pressure, for example,through its wall, that is greater than about 2 psi.

In accordance with another embodiment of the present invention,reservoir system 14 comprises a plurality of vessels or reservoirs, eachvessel, in turn can have several inlets positioned at various locationson each vessel. Each vessel may have one or several outlets, which canbe positioned at various locations depending on, among other things,demand or flow rate to point of use 18, capacity or efficiency ofelectrodeionization device 12 as well as capacity or hold up of thereservoir system. Reservoir system 14 can further comprise variouscomponents or elements that perform desirable functions or avoidundesirable consequences. For example, reservoir system 12 can havevessels having internal components, such as baffles that are positionedto minimize any internal flow currents. In some cases, reservoir system14 can have auxiliary or external components, including, but not limitedto, pressure release valves designed to relieve undesirable internalpressure and avoid or at least reduce the likelihood of rupture andexpansion systems that can accommodate volumetric changes associatedwith temperature changes, for example, a thermal expansion tank, that isdesigned for maintaining a desired operating pressure. The size andcapacity of such a thermal expansion tank will depend on several factorsincluding, but not limited to, the total volume of water, the operatingtemperature and pressure of the reservoir system.

In accordance with another embodiment of the present invention,treatment system 10 can include a circulation line that fluidly connectsat least one outlet of electrodeionization device 12. For example,circulation line 32 may connect to a manifold outlet (not shown), whichcollects liquid exiting a compartments, typically similar servicecompartments, in particular, depleting or concentrating compartments.Circulation line 32 can also be connected to an inlet ofelectrodeionization device 12 through, as illustrated in FIG. 1, pump 20b and valves 22 a and 22 b.

Electrodeionization device 12 can also comprise one or moreelectrodeionization stages, as described by Ganzi et al., in U.S. Pat.No. 5,316,637, which is incorporated herein by reference in itsentirety. In each stage, a stack of depleting and concentratingcompartments is positioned between first and second electrodes.According to one embodiment of the invention, each stage ofelectrodeionization device 12 includes a plurality compartments, eachcompartment defined, in part, by exterior membranes at either endthereof. A membrane of at least one compartment can co-extensivelycontact a membrane of an adjacent compartment; and according to oneembodiment, all the compartment in the stack can be arranged adjacenteach other with membranes of adjacent compartment in co-extensivecontact with each other. Such an arrangement is described by Gallagheret al., in U.S. Pat. No. 5,736,023, which is incorporated herein byreference in its entirety.

As illustrated in the embodiment of FIG. 1, electrodeionization device12 typically includes a first compartment 34 and an adjacent compartment36, the first and second compartment separated by an ion selectivemembrane 38 positioned therebetween. According to one embodiment of theinvention, first compartment 34 can serve as a depleting compartment andsecond compartment 36 can serve as a concentrating compartment. Notably,electrodeionization device 12 is schematically illustrated with a singledepleting compartment and a single concentrating compartment; it isshown as such for illustration only. Thus, according to one preferredembodiment of the invention, a plurality of depleting compartment and asingle concentrating compartments, defining a stage, would be arrangedbetween electrodes of the electrodeionization device.

First compartment 34 can include a first port 40 and a second port 42.Similarly, second compartment 36 can include a first port 44 and asecond port 46. In accordance with one embodiment of the presentinvention, first port 40 and second port 42 can be positioned atopposite ends of first compartment 34 and first port 44 and second port46 can be positioned at opposite ends of second compartment 36. Firstports 40 and 44 may serve as liquid entrances into their respectivecompartments. Correspondingly, second ports 42 and 46 may serve asliquid exits of their respective compartments.

In accordance with another embodiment of the present invention,electrodeionization device 12 can comprise a plurality of first andsecond compartments. Each of the first compartments can comprise a firstport and a second port. The plurality of first ports can be commonlyfluidly connected to a first port manifold 48 and the plurality ofsecond ports can be commonly fluidly connected to a second port manifold50. Similarly, each of the second compartments can comprise a first portand a second port. The plurality of second compartment first ports canbe commonly fluidly connected to a first port manifold 52 and theplurality of second compartment second ports can be commonly fluidlyconnected to a second port manifold 54.

First compartment 34 and second compartment 36 can be connected to aliquid circuit network having a plurality of fluid pathways or circuitsdefined by conduits, manifolds and valves. In one embodiment of theinvention, shown in FIG. 1, a first liquid circuit can comprise fluidconnections from reservoir system 14 to either of first compartment 34or second compartment 36, through pump 20 a, filter 24 a, valves 22 aand 22 b and manifolds 48 and 52. The first fluid circuit can furthercomprise fluid connections from first compartment 34 and secondcompartment 36 to reservoir system 14, through manifolds 50 and 54 andvalves 22 c and 22 d. In another embodiment of the invention, treatmentsystem 10 can comprise a second liquid circuit through first compartment34 or second compartment 36 and circulation line 32. In some cases, thesecond fluid circuit fluidly can connect circulation line 32 to firstcompartment 34 or second compartment 36 through pump 20 b, filter 24 band any of valves 22 a or 22 b. The second fluid circuit can furthercomprise fluid connections through manifolds 48 and 52. Moreover, thesecond liquid circuit can further comprise fluid connections throughmanifold 50 or manifold 54 to any of valves 22 c and 22 d.

As used herein, the term liquid circuit is intended to define aparticular connection and arrangement of valves and lines that allows aliquid stream to flow therein.

Other embodiments of the present invention will be described withreference to FIGS. 2A-2D. In the figures, darkened, bold lines representpathways through which liquid can flow according to the described liquidcircuit. For purposes of illustration, the various embodiments of thepresent invention will be described in terms of water purification.However, it is to be understood that the treatment of any liquidtreatable by electrodeionization techniques can benefit for employmentof the systems and methods of the present invention.

In FIG. 2A, a first liquid circuit is illustrated in which feed liquid,for example tap water, brackish water or pre-treated semi-pure water canenter treatment system 10 through a point of entry (not shown).Accordingly, in one embodiment of the invention, liquid to be treatedcan flow in a first liquid circuit from an outlet 60 of reservoir system14 through conduit 62, valve 22 a, pump 20 a, optionally through filter24 a and manifold 52 into compartment 36 through port 44. The firstliquid circuit can further comprise connections to compartment 36through port 46 to manifold 54, valve 22 d, conduit 64 and to reservoirsystem 14 through inlet 66. Valves 22 a and 22 d can be actuated toallow flow through the above described first liquid circuit. Thus, thefirst liquid circuit can provide liquid to be treated from reservoirsystem 14 to electrodeionization device 12 and can transfer the treatedliquid and store it in reservoir system 14.

The present invention provides a second liquid circuit in treatmentsystem 10. According to one embodiment of the invention, the secondliquid circuit can allow a concentrating stream to flow in a closed loopthrough one compartment of electrodeionization device 12. As illustratedin the schematic diagram of FIG. 2B, the second liquid circuit cancomprise a connection to and from circulation line 32 and to and fromcompartment 34 through valve 22 b, pump 20 b, optionally through filter24 b, into manifold 48 and can enter compartment 34 through port 40. Thesecond liquid circuit can allow a liquid to exit compartment 34 throughport 42 and manifold 50 and return to compartment 34 through circulationline 32 and manifold 48. According to one embodiment of the invention,the concentrating stream flowing in the second liquid circuit cancomprise ionic species, which have migrated from compartment 36 throughion selective membrane 38 into compartment 34. In some cases, theconcentrating stream flowing in the second liquid circuit may bedischarged or transferred to drain 30 according to a predeterminedschedule. Transfer to drain 30 may be accomplished by, for example,opening a drain valve (not shown) as necessary.

In another embodiment, illustrated in FIG. 2C, the present inventionprovides a third liquid circuit fluidly connecting reservoir system 14to compartment 34 of electrodeionization device 12. The third liquidcircuit can include connections to and from filter 24 b. Typically, thethird liquid circuit can comprise connections from outlet 60 ofreservoir system 14 to conduit 62 to valve 22 b to pump 20 b to manifold48 and to port 40 of compartment 34. The third fluid circuit can furthercomprise connections from port 42 to manifold 50 to valve 22 c toconduit 64 and to inlet 66 of reservoir system 14. In the third liquidcircuit, fluids to be treated from reservoir system 14 typically flowsinto compartment 34. Produced treated water can be transferred toreservoir system 14.

In another embodiment, the present invention can provide a fourth liquidcircuit that provides a connection from an outlet of a concentratingcompartment to an inlet of the same concentrating compartment ofelectrodeionization device 12. As illustrated in the schematic diagramof FIG. 2D, the fourth liquid circuit can connect outlet 46 ofcompartment 36 to manifold 54 to valve 22 d which, in turn, can connectto circulating line 32. The fourth liquid circuit also can provide aconnection from circulating line 32 to valve 22 a to pump 20 a and toport 44 of compartment 36 through manifold 52. This liquid circuit caninclude a connection to drain 30 so that a concentrating stream thattypically flows in the fourth liquid circuit can be discharged.

In another embodiment, as illustrated in FIG. 3A, the present inventionprovides for flushing of electrodeionization device 12 using treatedwater or at least partially treated water. Flushing ofelectrodeionization device 12 can be performed by transferring treatedwater using pumps 20 a and 20 b through valves 22 a and 22 b and,optionally, through filters 24 a and 24 b into compartments 34 and 36.This first flushing circuit can be performed sequentially so thatcompartment 36 is flushed with treated water before compartment 34 isflushed with the treated water that flows out of compartment 36. Thefluid direction arrows 56 show that treated water, from reservoir 14,can be directed by valve 22 a to flow through pump 20 a to manifold 52before entering port 44 of compartment 36. In this way, treated watermay be used to replace or flush out any liquid accumulated incompartment 36. Continued operation of pump 20 a, transferring treatedliquid from reservoir 14, can force any liquid upstream of the treatedflushing liquid to exit through port 46 and flow into manifold 54,which, eventually, can be redirected by valve 22 c into recirculationline 32. Valve 22 b can connect circulation line 32 pump 20 b, which, inturn, can allow the treated liquid to flow through manifold 48 and entercompartment 34 through port 40. Continued flow of the treated water, bythe use of any of pumps 20 a and 20 b, or optionally, the coordinateduse of both pumps, as well as properly oriented valves 22 a, 22 b, 22 cand 22 d can allow substantially all or most of the process lines,especially the wetted parts of treatment system 10, to be flushed withtreated water from reservoir 14. In some cases, the treated water usedto flush electrodeionization device 12 has a low LSI or is sufficientlypure to accommodate and meet the requirements of point of use 18 afterbeing mixed with any liquid having undesirable ionic species. Thepresent invention further provides a flushing system which replaces theliquid contents of electrodeionization device 10 with a liquid having alow LSI and, it is believed, provides inhibition of any scale formation.The liquid can be returned to reservoir system 14. As used herein, lowLSI water has a LSI of less than about 2, preferably, less than about 1,and more preferably, less than about zero. In some embodiments, thepresent invention provides treated liquids, such as water, having a lowconductivity. As used herein, a low conductivity liquid has aconductivity of less than about 300 μS/cm, preferably less than about220 μS/cm and more preferably, less than about 200 μS/cm.

In another embodiment, the present invention can provide a secondflushing circuit that can replace any liquid having a tendency to scalethat may be present in treatment system 10. In the embodimentschematically illustrated in FIG. 3B, liquid, which may be treatedwater, from reservoir 14 flows in parallel through valves 22 a and 22 bthrough pump 20 a and 20 b into first and second compartments 34 and 36.Treated water can flow into manifolds 48 and 52 and enter thecompartments through 40 and 44, respectively. Continued flow of thetreated water can displace any liquid that may tend to form scale incompartments 34 and 36. Flushing can be continued by operating pumps 20a and 20 b so that treated water can flow out through ports 42 and 46and into manifold 50 and 54, respectively, and eventually be directed byvalves 22 c and 22 d to return to reservoir 14. In this arrangement ortechnique, flushing fluid, such as treated water, can replace any liquidthat may have accumulated in treatment system 10. As with the earlierdescribed embodiments, the flushing arrangements or techniques canreplace any liquid that may tend to form scale with a liquid that has alow LSI or a liquid that has little or no tendency to form scale.Similarly, the flushing liquid may be returned to reservoir system 14.

In some embodiments of the invention, reservoir system 14 comprises apressurized vessel or a vessel that has inlets and outlets for fluidflow such as an inlet 58 and an outlet 60. Inlet 58 is typically fluidlyconnected to point of entry 16 and outlet 60 is typically fluidlyconnected to a water distribution system or a point of use 18. Reservoirsystem 14 can have several vessels, each vessel, in turn, can haveseveral inlets positioned at various locations. Similarly, outlet 60 canbe positioned on each vessel at various locations depending on, amongother things, demand or flow rate to point of use 18, capacity orefficiency of electrodeionization device 12 and capacity or hold-up ofreservoir system 14. Reservoir system 14 can further comprise variouscomponents or elements that perform desirable functions or avoidundesirable consequences. For example, reservoir system 14 can havevessels having internal components, such as baffles that are positionedto disrupt any internal flow currents within the vessels of reservoirsystem 14. In accordance with some embodiments of the present invention,reservoir system 14 can comprise a heat exchanger for heating or coolingthe fluid. For example, reservoir system 14 can comprise a vessel with aheating coil, which can have a heating fluid at an elevated temperaturerelative to the temperature of the fluid in the vessel. The heatingfluid can be hot water in closed-loop flow with a heating unit operationsuch as a furnace so that the heating fluid temperature is raised in thefurnace. The heating fluid, in turn, can raise the vessel fluidtemperature by heat transfer. Other examples of internal or additionalcomponents include, but are not limited to, pressure relief valvesdesigned to relieve internal pressure of any vessels and avoid or atleast reduce the likelihood of vessel rupture. In yet another embodimentof the present invention, reservoir system 14 comprises a thermalexpansion tank that is suitable for maintaining a desired operatingpressure. The size and capacity of a thermal expansion tank will dependon factors including, but not limited to, the total volume of water, theoperating temperature and pressure of the reservoir system.

In operation, reservoir system 14 is typically connected downstream ofpoint of entry 16 and fluidly connected in-line, such as in acirculation loop, with an electrochemical device 12 such as anelectrodeionization device. For example, water from point of entry 16can flow into inlet 58 and can mix with the bulk water contained withinreservoir system 14. Bulk water can exit reservoir system 14 throughoutlet 60 and can be directed to point of use 18 or through pumps 20 aand 20 b into electrochemical device 12 for purification or removal ofany undesirable species. Treated water leaving electrochemical device 12can mix with water from point of entry 16 and enter reservoir system 14through inlet 60. In this way, a loop is formed between reservoir system14 and electrodeionization device 12 and feedwater from point of entry16 can replenish water demand created by and flowing to point of use 18.

The electrochemical device can comprise any treatment apparatus orsystem that purifies or treats a fluid, such as water, by removing, atleast partially, any undesirable species, such as hardness-causingspecies. Examples of such electrochemical devices includeelectrodionization devices, electrodialysis devices and capacitivedeionization devices. Notably, the systems and techniques of the presentinvention can utilize other treatment apparatus or systems. For example,the present invention can utilize a reverse osmosis apparatus as atreatment device and the various arrangements and techniques describedherein can be utilized to minimize or remove any hardness depositspresent in such a system.

Point of entry 16 provides or connects water from a water source to thetreatment system. The water source can be a potable water source, suchas municipal water source or well water or it can be a non-potable watersource, such as a brackish or salt-water source. In such instances, anintermediate purification or treatment system typically purifies thewater for human consumption before it reaches point of entry 16. Thewater typically contains dissolved salts or ionic or ionizable speciesincluding sodium, chloride, chlorine, calcium ions, magnesium ions,carbonates, sulfates or other insoluble or semi-soluble species ordissolved gases, such as silica and carbon dioxide. Moreover, the watercan contain additives such as fluoride, chlorate and bromate.

In another embodiment of the present invention, treatment system 10includes a water distribution system, which in turn connects to a pointof use. The water distribution system can comprise components that arefluidly connected to provide water, typically treated water, fromreservoir system 14 to point of use 18. The water distribution systemcan comprise any arrangement of pipes, valves, tees, pumps and manifoldsto provide water from reservoir system 14 to one or several points ofuse 18 or to any component of treatment system 10. In one embodiment,the water distribution system comprises a household or residential waterdistribution network including, but not limited to, connections to asink faucet, a shower head, a washing machine and a dishwasher. Forexample, system 10 may be connected to the cold or hot, or both, waterdistribution system of a household.

In accordance with another embodiment of the present invention,treatment system 10 also comprises a sensor 28, typically a waterproperty sensor, which measures at least one physical property intreatment system 10. For example, sensor 28 can be a device that canmeasure turbidity, alkalinity, water conductivity, pH, temperature,pressure, composition or flow rate. Sensor 28 can be installed orpositioned within treatment system 10 to measure a particularlypreferred water property. For example, sensor 28 can be a waterconductivity sensor installed in reservoir system 14 that measures theconductivity of the stored water, which can be an indication of thequality of the water available for service in point of use 18. Inanother embodiment of the invention, sensor 28 can comprise a series ora set of sensors. The set of sensors can be constructed, arranged orconnected to controller 26 so that controller 26 can monitor,intermittently or continuously, the quality of water. In such anarrangement, the performance of treatment system 10 can be optimized asdescribed below. Other embodiments of the invention may comprise acombination of sets of sensors in various locations throughout treatmentsystem 10. For example, sensor 28 can be a flow sensor measuring a flowrate to a point of use 18 and further include any of a nephelometer, pH,composition, temperature and pressure sensor monitoring the operatingcondition of treatment system 10.

In accordance with another embodiment of the present invention,treatment system 10 can further comprise a pretreatment system 24designed to remove a portion of any undesirable species from the waterbefore the water is introduced to, for example, reservoir system 14 orthe treatment device, e.g., the electrochemical device. Examples ofpretreatment systems include, but are not limited to, reverse osmosisdevices, which are typically used to desalinate brackish or salt water.Notably, a carbon or charcoal filter may be necessary to remove at leasta portion of any chlorine or any species that may foul or interfere withthe operation of electrochemical device.

Pretreatment system 24 can be positioned anywhere within treatmentsystem 10. For example, pretreatment system 24 can be positionedupstream of reservoir system 14 or downstream of reservoir system 14 butupstream of electrodeionization device 12 so that at least some chlorinespecies are retained in reservoir system 14 but are removed beforeliquid enters electrodeionization device 12. Pretreatment system 24 cancomprise a filter or an arrangement of filters. As shown in FIG. 1,pretreatment system 24 comprises filters 24 a and 24 b upstream ofcompartments 34 and 36. In other cases, pretreatment system 24 cancomprise a filter upstream of reservoir system 14 as well as filters 24a and 24 b between pumps 20 a and 20 b and compartments 36 and 34.Filters 24 a and 24 b can be any of a particulate, carbon, iron filteror combinations thereof.

In accordance with other embodiments of the present invention, thetreatment system can further comprise pre or post treatment apparatus orsystems disposed in any part thereof to allow decontamination orinactivation of any microorganisms such as bacteria that may accumulatein any component of the treatment system. For example, a pretreatmentapparatus may be fluidly connected to a distribution system of thepresent invention. In other embodiments of the invention, a posttreatment device can treat fluid prior to being delivered to a point ofuse. Examples of such apparatus or systems that can destroy orinactivate microorganisms include those that provide actinic radiation,or ultraviolet radiation, and/or ozone. Other examples of such devicesinclude those that remove bacteria by ultrafiltration ormicrofiltration. In accordance with other embodiments of the presentinvention, the treatment system can further include one or more chemicaldelivery systems that disinfects one or more components of the treatmentsystem. For example, a chemical treatment system can be fluidlyconnected to any component of the treatment system to deliver a chemicalthat destroys or renders any bacteria inactive. Examples of suchchemicals include, but are not limited to, acids, bases or otherdisinfecting compounds such as alcohols. In further embodiments of thepresent invention, a hot water disinfecting apparatus can be fluidlyconnected to the treatment system of the present invention. The hotwater disinfecting system can provide hot water that destroys orinactivates any bacteria that may accumulate in any component of thetreatment system.

In yet another embodiment of the present invention, treatment system 10further comprises a controller 26 that is capable of monitoring andregulating the operating conditions of treatment system 10 including itscomponents. Controller 26 is typically a microprocessor-based device,such as a programmable logic controller (PLC) or a distributed controlsystem, that receives or sends input and output signals to and fromcomponents of treatment system 10. In one embodiment of the invention,controller 26 can be a PLC that sends a signal to power source (notshown), which supplies power to electrodeionization device 12 or asignal to a motor control center that energizes the motors of pumps 20 aand 20 b. In certain embodiments of the invention, controller 26regulates the operating conditions of treatment system 10 in open-loopor closed-loop control scheme. For example, controller 26, in open-loopcontrol, can provide signals to the treatment system such that water istreated without measuring any operating condition. In contrast,controller 26 can control the operating conditions in closed-loopcontrol so that operating parameters can be adjusted depending on anoperating condition measured by, for example, sensor 28. In yet anotherembodiment of the invention, controller 26 can further comprise acommunication system such as a remote communication device fortransmitting or sending the measured operating condition or operatingparameter to a remote station.

In accordance with another embodiment of the present invention,controller 26 can provide a signal that actuates valves 22 a, 22 b, 22c, and 22 d so that liquid flow is directed based on a variety ofparameters including, but not limited to, the quality of water frompoint of entry 16, the quality of water to point of use 18, the demandor quantity of water to point of use 18, the operating efficiency orcapacity of electrodeionization device 12, or any of a variety ofoperating conditions, such as turbidity, alkalinity, water conductivity,pH, composition, temperature, pressure and flow rate. In one embodimentof the invention, controller 26 can receive signals from sensor 28 sothat controller 26 can be capable of monitoring the operating parametersof treatment system 10. For example, sensor 28 can be a waterconductivity sensor positioned within reservoir system 14 so that thewater conductivity in reservoir system 14 can be monitored by controller26. Controller 26 can, based on the water quality measured by sensor 28,control a power source, which can provide an electric field toelectrodeionization device 12. So, in operation, controller 26 canincrease or decrease or otherwise adjust the voltage and currentsupplied from power source 24 to, for example, electrodeionizationdevice 16.

In yet another embodiment, the present invention provides for adjustingan operating parameter, for example, the rate of discharge to drain 30or the period during discharge, as a function of at least one measuredparameter such as the system operating pressure. For example, the periodduring which a valve (not shown), in FIG. 1, is actuated open to drain30 can be adjusted based on the measured pressure of the liquid suppliedto point of use 18. In some cases, the valve may be actuated open toreduce the measured pressure or it may be minimally actuated, dependingon the type of valve, when the measured pressure is below apredetermined value. Such a secondary control scheme can be incorporatedor nested within any of the existing control loops actuating the valvedescribed above.

In accordance with another embodiment of the present invention, thevalve can serve as part of a pressure control loop as well as a part ofa concentrate discharge control loop. For example, the valve can beactuated by controller 26 when the measured conductivity of theconcentrate stream reaches a set point. A separate pressure control loopincorporating the valve can be superimposed or nested within an existingcontrol loop to relieve pressure in system 10. In any of theabove-mentioned control schemes, the control loops can incorporatefeedback as well as any of proportional, derivative, integral or,preferably, a combination thereof. In another embodiment of theinvention, a control loop that directs the discharge of a concentratestream to drain 30 can have a nested control loop parameter that dependson or factors in the pressure of liquid delivered to point of use 18 toprovide a control signal.

In another embodiment of the present invention, controller 26 canreverse the direction of the applied current from power source toelectrodeionization device 12 according to a predetermined schedule oraccording to an operating condition, such as the water quality or anyother operating parameter. Polarity reversal has been described by, forexample, Giuffrida et al., in U.S. Pat. No. 4,956,071, which isincorporated herein by reference in its entirety.

Controller 26 can be configured or configurable by programming or can beself-adjusting such that it is capable of maximizing any of the servicelife and the efficiency of or reducing the operating cost of treatmentsystem 10. For example, controller 26 can comprise a microprocessorhaving user-selectable set points or self-adjusting set points thatadjusts the applied voltage and current to an electrochemical devicesuch as an electrodeionization device, the flow rate through theconcentrating and depleting compartments of the electrodeionizationdevice or the discharge flow rate to drain 30 from theelectrodeionization device or the pretreatment system or both. Othermodifications and equivalents of the controller, as part of thetreatment system disclosed, will occur to persons skilled in the artusing no more than routine experimentation. For example, theincorporation of adaptive, self-adjusting, or self-diagnosing techniquescapable of alerting changing the operating parameters based on a varietyof input conditions such as rate of water use or time of water use, arebelieved to be within the scope and spirit of the invention. Controller26 can incorporate dead band control to reduce the likelihood ofunstable on/off control or chattering. Dead band refers to the range ofsignal outputs that a sensor provides without necessarily triggering aresponsive control signal. The dead band may reside, in some embodimentsof the invention, intrinsically in the sensor or may be programmed aspart of the control system, or both. Dead band control can avoidunnecessary intermittent operation by smoothing out measurementexcursions. Such control techniques can prolong the operating life ormean time before failure of the components of treatment system 10. Othertechniques that can be used include the use of voting, time-smoothing ortime-averaging measurements or combinations thereof.

In another embodiment of the present invention, water, typically fromwaste stream, to auxiliary use can serve or provide additional orsecondary benefits. For example, waste stream, rather than going todrain 30, may be used to provide irrigating water to any residential,commercial or industrial use, such as for irrigating, for recycling orfor recovery of collected or concentrated salts.

The treatment system can comprise a fluid circuit that can providetreated or, in some cases, softened water to an electrode compartment ofthe electrochemical device. The fluid circuit can comprise fluidconnections from a treated water source to the electrode compartments ofthe electrochemical device. The fluid circuit can also comprise apretreatment unit, such as a carbon filter that can remove any species,such as chlorine, which can interfere with the operation of theelectrochemical device. The fluid circuit can also include fluidconnections to at least one of the depleting and the concentratingcompartments of, for example, the electrodeionization device, forexample, downstream of the pretreatment unit. The fluid circuitconnections, in one embodiment of the invention, provides connections sothat fluid exiting the electrode compartments can be, for example, mixedtogether or mixed with fluid to be treated in the depleting compartment.The fluid circuit can also comprise pumps and valves that can directfluid flow to and from the electrochemical device as well as to and fromthe reservoir system. In some cases, the fluid circuit is arranged toprovide fluid connections that creates parallel flow paths through theelectrode compartments of the electrodeionization device. Otherarrangements and configurations are considered to be within the scope ofthe present invention including, for example, serial flow paths from oneelectrode compartment to the other, the use of single, multiple ordedicated pretreatment units as well as multiple or staged treatmentunits including, but not limited to, reverse osmosis, ion exchange andelectrodeionization devices, or combinations thereof, in the fluidcircuit.

The treatment system can comprise a fluid circuit that provides fluidconnections from a depleting compartment to at least one electrodecompartment of the electrodeionization device. Such an arrangement canprovide treated water, preferably water having low LSI, to the electrodecompartment. The fluid circuit can be arranged so that the fluid flowpaths can be in series or in parallel through the electrodecompartments. The fluid circuit can further comprise fluid connectionsto allow the fluid that would exit the electrode compartment to bedelivered to a point of use via, for example, a water distributionsystem. In some arrangements according to the present invention, thefluid circuit can comprise fluid connections so that untreated fluid canbe mixed with fluid that would exit any of electrode compartments; themixture can be delivered to the point of use. In another embodiment ofthe invention, the fluid circuit can further comprise fluid connectionsto and from a reservoir system so that, for example, treated fluid thatwould exit the depleting compartment can be transferred to the reservoirsystem and mixed with untreated fluid from the point of entry and themixture can be delivered to the point of use and, optionally, to theelectrode compartments of the electrodeionization device in parallel orseries flow paths. Other arrangements and combinations including, forexample, the mixing of treated and untreated water to produce a mixedelectrode compartment flushing fluid is considered to be within thescope of the present invention.

The present invention will be further illustrated through the followingexample, which is illustrative in nature and is not intended to limitthe scope of the invention.

EXAMPLE

An in-line pressurized treatment system, schematically shown in FIG. 4was assembled and evaluated. The treatment system 10 comprised anelectrodeionization module 12 and a pressurized storage vessel 14.Water, from point of entry 16, was introduced into pressurized storagevessel 14 through inlet 58 and was circulated using pumps 20 a and 20 band passed through pretreatment units 24 a and 24 b andelectrodeionization device 12. The treatment system was controlled by aprogrammable controller (not shown) based on the measured waterconductivity, as measured by any of sensors 28 a, 28 b, 28 c, and 28 d.

Electrodeionization device 12 comprised of a 10-cell pair stack withflowpaths that were about 7.5 inches long and about 2.5 inches wide.Each cell was filled with about 40% AMBERLITE® SF 120 resin and about60% AMBERLITE® IRA 458 resin, both available from Rohm & Haas Company,Philadelphia, Pa. The electrodeionization device had an expandedtitanium electrode coated with ruthenium oxide.

The controller was a MICROLOGIX™ 1000 programmable controller availablefrom Allen-Bradley Company, Inc., Milwaukee, Wis. Theelectrodeionization device was set to start up either by a flow switchsignal or when the water conductivity of the outlet stream leaving thepressurized vessel was higher than a set point. The electrodeionizationdevice operated until the conductivity reached the set point. The feedfrom the electrodeionization device was circulated from the pressurizedvessel via a second feed pump. The polarity of the electric fieldapplied to the electrodeionization device was reversed about every 15minutes. In addition to controlling the components ofelectrodeionization device 12, the PLC collected, stored and transmittedmeasured data from sensors 28 a, 28 b, 28 c, and 28 d.

Pressurized vessel 14 was a 10-inch diameter fiberglass vessel withabout a 30-gallon capacity. Pressurized vessel 14 was fitted with avalve head and a center manifold pipe. The concentrate stream leavingthe electrodeionization device was partially circulated and partiallyrejected to a drain 30 by actuating valves 22 c, 22 d, and 22 e. Make-upwater, from point of entry 16, was fed into the circulating stream tocompensate for any water that was rejected to drain 30.

The pretreatment units 24 a and 24 b each comprised of an aerationiron-filter with a 25-micron rating, a 20 inch×4 inch sediment filterand a 20 inch×4 inch carbon block filter.

In one flow direction, water from pressure vessel 14 was pumped by pump20 a, through valve 22 a, to pretreatment unit 24 a before beingintroduced to the depleting compartments of electrodeionization device12. Treated water from electrodeionization device 12 was directed byvalve 22 a to storage in pressure vessel 14. Fluid collecting removedionic species was circulated by pump 20 b through pretreatment unit 24b, and the concentrating and electrode compartments ofelectrodeionization device 12 by activating valves 22 d and 22 b. Whenthe polarity of the applied electric field was reversed, the flowdirections were correspondingly adjusted so that pump 20 a, pretreatmentunit 24 a, and valve 22 a circulated the liquid accumulating ionicspecies. Similarly, water to be treated was pumped from pressure vessel14 using pump 20 b through valve 22 d to pretreatment unit 24 b beforebeing introduced and treated in the depleting compartments ofelectrodeionization device 12. Treated water was directed by valve 22 dto pressure vessel 14.

The flow rate of treated water, as measured by flow indicator 28 c, to apoint of use 18 from outlet 60 of pressurized vessel 14 was regulated byadjusting valves 22 f and 22 g. To discharge concentrate or wastestream, valve 22 e was operated as necessary. Water from point of entry16 was used to restore and replace fluid that was discharged to drain 30or consumed in point of use 18.

The treatment system was operated until a target set point of about 220μS/cm was reached and stable for about one minute. The applied voltageto the electrodeionization device was about 46 volts. The flow ratesinto the depleting and concentrating compartments were maintained atabout 4.4 liters per minute. The reject flow rate was controlled todischarge about 270 ml about every 30 seconds. The pressure in thevessel was about 15 psig to about 20 psig.

FIG. 5 shows the measured conductivity, of the various streams in thetreatment system as a function of run time. Tables 1 and 2 summarize themeasured properties of the various streams of the treatment system atthe start and end of the test, respectively. The data presented in Table1 showed that the initial feed stream, labeled as tankout conductivityin FIG. 5, into electrodeionization device 12, with a conductivity ofabout 412 μS/cm, was treated to produce an initial dilute stream,labeled as stackout conductivity in FIG. 5, having a conductivity ofabout 312 μS/cm, without a substantial pH change. Similarly, at the endof the test run, water, having a conductivity of about 221 μS/cm, wastreated to produce lower conductivity water, of about 164 μS/cm, withouta substantial pH change. It is believed that the lower conductivity ofthe feed stream at the end of the test run reflected the effect ofcirculation, which effectively removed undesirable species over severalpasses. Thus, the data shows that the system schematically illustratedin FIG. 4 can treat or soften water that is suitable for household orresidential use. TABLE 1 Stream properties at the start of the test run.Feed Stream Reject Stream Product Stream pH 8.19 8.3 8.02 Conductivity(μS/cm) 412 944.9 312.0

TABLE 2 Stream properties at the end of the test run. Feed Stream RejectStream Product Stream pH 8.37 8.33 7.75 Conductivity (μS/cm) 221 833.8164

The present invention has been described using water as the liquid butshould not be limited as such. For example, where reference is made totreated water, it is believed that other fluids can be treated in thesystem or according to the method of the present invention. Moreover,where reference is made to a component of the system, or to a step ofthe method, of the present invention that adjusts, modifies, measures oroperates on water or water property, the present invention is believedto be applicable as well. Thus, the fluid to be treated may be a fluidthat is a mixture comprising water. Accordingly, the fluid can be aliquid that comprises water.

Those skilled in the art would readily appreciate that all parametersand configurations described herein are meant to be exemplary and thatactual parameters and configurations will depend on the specificationapplication for which the systems and methods of the present inventionare used. Those skilled in the art should recognize or be able toascertain using no more than routine experimentation many equivalents tothe specific embodiments of the invention described herein. For example,the present invention includes the use of other unit operations such as,but not limited to, reverse osmosis and ultraviolet device. It is,therefore, to be understood that the further embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto, the invention may be practiced otherwise asspecifically described. The invention is directed to each individualfeature, system, or method described herein. In addition, anycombination of two or more such features, systems, or methods providedat such features, systems, or methods that are not mutuallyinconsistent, is included within the scope of the present invention.

1. A treatment system comprising: an electrochemical device comprising afirst compartment and a second compartment; a first liquid circuitfluidly connecting a first compartment inlet and a first pump; a secondliquid circuit fluidly connecting a second compartment outlet to asecond compartment inlet and a second pump; and a third liquid circuitfluidly connecting the second compartment inlet and the second pump. 2.The treatment system of claim 1, further comprising a first filterdevice fluidly connected to the first pump.
 3. The treatment system ofclaim 2, further comprising a second filter device fluidly connected tothe second pump.
 4. The treatment system of claim 1, further comprisinga point of entry fluidly connected to a water reservoir.
 5. Thetreatment system of claim 1, further comprising a water distributionsystem fluidly connected to a water reservoir.
 6. The treatment systemof claim 1, further comprising a point of use fluidly connected to awater reservoir.
 7. The treatment system of claim 1, further comprisinga sensor measuring at least one operating parameter of the treatmentsystem.
 8. The treatment system of claim 1, further comprising a fourthliquid circuit fluidly connecting a water reservoir to the firstcompartment inlet and the first compartment outlet to the secondcompartment inlet.
 9. The treatment system of claim 1, furthercomprising a post treatment system fluidly connected downstream of theelectrochemical device and upstream of a point of use.
 10. A treatmentsystem comprising: an electrochemical device comprising a firstcompartment comprising a first compartment outlet and a firstcompartment inlet and a second compartment comprising a secondcompartment outlet and a second compartment inlet, the electrochemicaldevice fluidly connected to a point of entry; a first pump fluidlyconnectable to the first compartment outlet and to the first compartmentinlet; a second pump fluidly connectable to the second compartmentoutlet and to the second compartment inlet; and a circulation linefluidly connectable to at least one of the first or second compartmentoutlets.
 11. The treatment system of claim 10, wherein the circulationline is fluidly connectable to at least one of the first and secondpumps.
 12. The treatment system of claim 10, further comprising a firstvalve fluidly connecting the circulation line to the first pump.
 13. Thetreatment system of claim 12, further comprising a second valve fluidlyconnecting the circulation line to the second pump.
 14. The treatmentsystem of claim 10, further comprising a first valve fluidly connectingthe first compartment outlet to the circulation line.
 15. The treatmentsystem of claim 14, further comprising a second valve fluidly connectingthe second compartment outlet to the circulation line.
 16. The treatmentsystem of claim 15, further comprising a controller actuating at leastone of the first and second valves.
 17. The treatment system of claim10, further comprising a sensor measuring at least one operatingparameter of the treatment system.
 18. The treatment system of claim 10,further comprising a water reservoir fluidly connected to the point ofentry and a water distribution system fluidly connected to the waterreservoir.
 19. The treatment system of claim 10, further comprising adisinfectant source fluidly connectable to at least one of theelectrochemical device, the circulation line, the first pump, and thesecond pump.
 20. A method of treating a liquid comprising: establishinga first liquid circuit having liquid to be treated flowing therein froma reservoir to a first compartment inlet of an electrochemical devicethrough a first pump; establishing a second liquid circuit having aconcentrating liquid flowing therein from a second compartment outlet ofthe electrochemical device to a second compartment inlet through asecond pump; and establishing a third liquid circuit having liquid to betreated flowing therein from the reservoir to the second compartmentinlet through the second pump.
 21. The method of claim 20, furthercomprising establishing a fourth liquid circuit having the concentratingliquid flowing therein from the first compartment outlet to the firstcompartment inlet through the first pump.
 22. The method of claim 20,further comprising applying an electric field across the electrochemicaldevice.
 23. The method of claim 22, further comprising reversing apolarity of the applied electric field after establishing the thirdliquid circuit.
 24. The method of claim 20, wherein establishing thethird liquid circuit comprises actuating a first valve to direct theliquid to be treated to flow through the second pump.
 25. The method ofclaim 24, further comprising actuating a second valve to direct theconcentrating liquid to flow through the first pump.
 26. The method ofclaim 20, further comprising measuring at least one of a pressure,temperature, flow rate, pH, conductivity and composition of the liquid.27. The method of claim 20, further comprising flushing the first andsecond compartments with the treated liquid.
 28. The method of claim 20,further comprising flushing at least one of the first and second pumpswith the treated liquid.
 29. The method of claim 20, further comprisingestablishing a fourth liquid circuit having liquid from the reservoirflowing therein from the reservoir to the first and second compartmentsthrough the first and second pumps.
 30. The method of claim 29, whereinthe liquid from the reservoir has a negative LSI.
 31. The method ofclaim 20, further comprising delivering at least a portion of thetreated liquid to a point of use.
 32. The method of claim 31, furthercomprising post treating the treated liquid prior to delivering thetreated liquid to the point of use.
 33. The method of claim 20, furthercomprising disinfecting at least a portion of any component of any ofthe first liquid circuit, the second liquid circuit and the third liquidcircuit.
 34. A method of treating water comprising: passing at least aportion of water to be treated through a depleting compartment of anelectrochemical device through a first pump to produce the treatedwater; circulating a concentrating stream through a concentratingcompartment of the electrochemical device through a second pump; andcirculating the concentrating stream through the concentratingcompartment through the first pump.
 35. The method of claim 34, furthercomprising passing at least a portion of the water to be treated throughthe second pump.
 36. The method of claim 34, further comprising flushingthe first compartment while flushing the second compartment.
 37. Themethod of claim 34, further comprising flushing the first and secondcompartments and the first and second pumps with treated watersequentially.
 38. The method of claim 34, further comprising passing thewater from the reservoir through the first compartment after passing thewater through the second compartment.
 39. A method of treating watercomprising: passing water to be treated through an electrochemicaldevice to produce treated water; storing at least a portion of thetreated water in a water reservoir; and flushing a concentratingcompartment of the electrochemical device with the treated water. 40.The method of claim 39, wherein the treated water has a negative LSI.41. The method of claim 39, further comprising flushing the depletingcompartment.
 42. The method of claim 41, wherein flushing the depletingcompartment is performed during flushing the concentrating compartment.43. The method of claim 39, wherein flushing the first compartment andthe second compartment comprises flushing the first and the secondcompartment sequentially.
 44. The method of claim 39, wherein flushingthe first compartment and the second compartment comprises flushing thefirst and second compartments with treated water in parallel flow. 45.The method of claim 39, wherein flushing the first compartment and thesecond compartment comprises flushing the first and second compartmentswith treated water in series flow.
 46. The method of claim 39, furthercomprising exposing the treated water to actinic radiation or ozone. 47.The method of claim 39, further comprising passing the treated waterthrough a microfiltration or an ultrafiltration apparatus.
 48. Themethod of claim 39, further comprising exposing a disinfectant to atleast one of the electrochemical device and the water reservoir.
 49. Amethod of facilitating water purification comprising: providing anelectrochemical device comprising a first compartment and a secondcompartment; providing a first pump fluidly connectable to at least oneof a water reservoir, a first compartment outlet and a first compartmentinlet; providing a second pump fluidly connectable to at least one ofthe water reservoir, a second compartment outlet and a secondcompartment inlet; and providing a circulation line fluidly connectableto at least one of the first and second compartment outlets.
 50. Atreatment system comprising: an electrochemical device comprising afirst compartment and a second compartment; means for flowing a liquidto be treated from a water reservoir through the first compartment andcirculating a concentrating liquid through the second compartment; andmeans for flowing the liquid to be treated from the water reservoirthrough the second compartment and circulating the concentrating liquidthrough the first compartment.
 51. The treatment system of claim 50,wherein the electrochemical device comprises an electrodionizationdevice.